Is the Cosmos a Perennial?

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Cosmos produce an abundance of brightly colored, daisy-like flowers atop slender stems. With more than 20 species of these striking flowers, "Cosmos sulphureus" and "Cosmos bipinnatus" are the most common annual varieties grown in the United States. Others, such as the chocolate cosmos (Cosmos atrosanguineus), are perennials in U.S. Department of Agriculture plant hardiness zones 9 and 10.

Cosmos Sulphureus

"Cosmos sulphureus" produces yellow, orange, red or golden flowers. Common varieties include "Bright Lights," "Cosmic Yellow" and "Crest Red." Flowers may be either single or double blooms and come in a variety of sizes from dwarfs to plants 3 to 4 feet tall. Foliage on these plants is lobed with hairy edges.

Cosmos Bipinnatus

"Cosmos bipinnatus" produces flowers similar to other varieties, in the white, pink and rose range. Foliage is fernlike, giving the cosmos an airy appearance as the blooms sway in the summer breeze. Height ranges from 1 to 6 feet, depending on the cultivar. Common varieties include "Seashell Mix," "Daydream" and the "Sensation" series.

Cosmos Atrosanguineus

"Cosmos atrosanguineus," known as chocolate cosmos, produces lightly fragrant blooms that emit a chocolate or vanilla scent. Blooms consist of single petals that are closer to "oxblood red" than brown. These tuberous root cosmos grow as perennials in USDA plant hardiness zones 9 and 10. In USDA zones 8 and below, the tubers must be lifted in the fall and replanted in the spring.

Self Seeding

Because cosmos often self-seed, annual varieties may come back after their first year, giving the appearance of being perennials. When allowed to self seed in an undisturbed area, cosmos may produce well for several years without replanting.

Considerations

Cosmos are tolerant of a wide range of growing conditions, including poor soil and drought. They make attractive backgrounds, additions to meadow gardens or borders to walkways. These flowers attract butterflies to the garden as well.

About the Author

Nannette Richford is an avid gardener, teacher and nature enthusiast with more than four years' experience in online writing. Richford holds a Bachelor of Science in secondary education from the University of Maine Orono and certifications in teaching 7-12 English, K-8 General Elementary and Birth to age 5.